Petroleum is a non-renewable energy and cannot be recycled. It is a future tendency to replace the limited crude oil with algae having photosynthesis, carbon recycling, and the high efficiency of land use. There are several advantages in producing oil from microalgae, such as high oil-production, environmental benefits, and the eliminated need of occupying arable land. Some microalgae can even be grown in high salinity environments, so the salinization of land can be used as a place for cultivation of the microalgae. Without this process, these regions cannot be utilized to their full potential. Countries in the world such as the United States and China, are putting a lot of funding and research into microalgae oil. The usual method of extraction is to kill the algae and then extract the oil through the addition of chemical substances; the cost of such procedures is high. The direction of innovation currently contains a one hundred nanometer-sized circular silicon ball, as well as the use of genetically engineered algae to secrete oil automatically outside the cell. To this point, the nano circular silicon ball has not shown selective adsorption of oil and water, and secretion oil outside the cell still has not been successfully commercialized.
Nanomaterial is a new material which has drawn most attention in recent years. After the basic dimensions of the constituted material reach the nanometer scale, its performance will be a series of changes, i.e. nanometer effects (such as small size effect, volume effect, surface effect, quantum-size effect and macroscopic quantum tunneling effect etc.). Therefore, nanomaterials exhibit many novel properties different from conventional materials, and have broad application prospects. Scholars have begun to apply nanomaterials in the research of the oil field industry, such as deep profile control, heavy oil viscosity reduction, and low oil penetration. In an aspect of improving the efficiency of stripping oil, oil-displacing agent of nano membrane and oil-displacing agent of nano-emulsion, etc. have also appeared, but the oil displacement effect of the existing nano membrane displacing agent, nano-emulsion displacing agent, etc. is to lock the macroscopic oil system, and the size thereof can not be reduced to be permeable to algae body for extraction of algae oil. Thus, the expected result is not satisfactory. In addition to these directions, it still requires low energy consumption, more simplicity, greener preparation methods to improve the recovery ratio of the algae oil, and to reduce the damage during the extraction process for the algae. With that said, an inexpensive, environmentally friendly, algae oil extractable, good selective oil adsorption ability new nano-extraction agent for algae oil is to be developed.
In the oil extraction, transportation and processing, there may be a pollution problem of spilling oil in the device, organism and environment due to human or non-human factors. Researches have disclosed use of biological fibers and high molecular weight substances to adsorb oil substances, wherein the former contains coir, cotton fibers, pulp fibers, peat fibers, straw fibers, etc., and the latter contains PP, PS, PU. However, the high molecular weight substances are poor in the dissolution resistance for oil, and the follow-up burned processing will produce toxic gas molecules due to the pyrolysis and oxidation. The biological fibers have the disadvantages of poor oil/water extraction ratio and weak oil-absorbing ability due to high water adsorption rate. Therefore, when removing the oil pollution, the biological fibers often adsorb water and thus sink into the water, which are difficult to recycle and cause secondary pollution.
The patent reference [1] has reported using the porous materials to surround and adsorb oil, wherein the porous materials will swell after adsorbing oil. The patent reference [2] takes advantage of the low specific gravity of the oil-absorbing hydrophobic material to adsorb the oil floating on the surface of the (sea) water. In the present invention, the nanowires less than one micron with hydrophobic characteristics are used to achieve the purpose of adsorbing spilling oil. The size range of adsorbing oil molecules in the present invention includes but is not limited to, from the meter grade of a large area above the water to the micron grade of the micron pores.
[1] Japanese patent: JP 9267420A
[2] US patent: U.S. Pat. No. 4,061,567A
In order to overcome the drawbacks in the prior art, an oil extractor and the preparation method thereof are provided. The particular design in the present invention not only solves the problems described above, but is also easily implemented. Thus, the present invention has the utility for industry.